The invention relates generally to ink cartridges such as for ink jet printers, and in particular to an ink cartridge having an ink supply bag that is filled with a liquid ink.
The cross-referenced applications filed Aug. 16, 2001, particularly the one entitled INK CARTRIDGE WITH INTERNAL INK BAG AND METHOD OF FILLING, disclose a flexible bag filled with a liquid ink and a pair of housing halves that are connected together to contain the bag.
The bag when empty is placed in one of the housing halves. Then, the other housing half is connected to the one with the bag via an ultrasonic weld, and the bag is filled with the liquid ink.
The bag is filled to its capacity (its full volume) and is constrained in the cartridge housing by making contact with the cartridge housing at various spots. Since there are a number of spaces between the bag and the cartridge housing, there is room for the bag to expand. However, since the bag is filled to its capacity, the bag might possibly rupture if the cartridge housing is mechanically shocked, such as by dropping the cartridge housing onto a hard surface.
This problem is believed to be solved by the invention.
According to one aspect of the invention, an ink cartridge comprising a flexible bag filled with a liquid ink, and a cartridge housing that holds the bag, is characterized in that:
the bag is larger than the housing, but is folded to fit in the housing; and
the bag is filled to a predetermined percentage of its full volume to fill the bag to less than its capacity in order to prevent the bag from rupturing, but is filled sufficiently to substantially occupy the housing when folded. Preferably, the bag has a width that is greater than a width of the housing and has a length that is less than a length of the housing so that the bag need only be folded widthwise to fit in the housing.
According to another aspect of the invention, a method of preparing an ink bag to fit in a housing of an ink cartridge comprises:
providing a bag that is larger than the housing;
filling the bag to a predetermined percentage of its full volume to fill the bag to less than its capacity in order to prevent said bag from rupturing, but filling the bag sufficiently to substantially occupy said housing when folded; and
folding the bag to fit in the housing.